I am in the process of replacing my valve for my 2000 Ford Ranger. When I pop the hood it is back and to the right and has a couple of hoses attached to it. If you buy the part it is really easy to identify it with the replacement part.
It is located in the front driver's side of the engine bay connected to the vent canister. If you have a computer fault code related to it try cleaning the flow sensor that is just upstream of the valve. This thing gets filled with dust from the canister and causes the fault.